smartmontool + software-based RAID

[lbrtchx]

After reading smartmontool's FAQ and a number of other tutorials/info,
I still don't quite understand why is it that smartmontool is not or
can not be used in a -software- RAID conf. I also wonder why not so
many people do this
..
if you do a search on 'smartmontools "software raid"', you will see
many people reporting "weird beaviors" and all kinds of other
unwanted/unexpected etceteras.
..
There is a question in smartmontool's FAQ, "Can I monitor disks behind
RAID controllers?", that address -RAID controllers-. However, since
smartmontool works on a hardware level and -software- RAID works on an
OS level basically, I don't see why smartmontool is not used in
-software- RAID confs?
..
Also, could you point me to good links and possibly books on all
things hard drives including their physicall guts, tools to deal with
them, ...?
..
Something I notice is that some hard drives are placed vertically in
some computers and horizontally in some others, but I think (actually
it could be even proved) drives (their mechanical parts) are a lot less
taxed if they spin vertically, but I don't hear of anyone talking about
these kinds of things ...
..
thanks
lbrtchx

 

[Rod Speed]

After reading smartmontool's FAQ and a number of other
tutorials/info, I still don't quite understand why is it that
smartmontool is not or can not be used in a -software-
RAID conf. I also wonder why not so many people do this

Basically because not all software raid configs allow that.

if you do a search on 'smartmontools "software raid"',
you will see many people reporting "weird beaviors"
and all kinds of other unwanted/unexpected etceteras.

There is a question in smartmontool's FAQ, "Can I monitor disks
behind RAID controllers?", that address -RAID controllers-.
However, since smartmontool works on a hardware level

Not entirely.

and -software- RAID works on an OS level basically, I don't
see why smartmontool is not used in -software- RAID confs?

Essentially because not all software raid configs allow
that, because smartctl doesnt work exclusively at the
hardware level. It still gets access via the drivers.

Also, could you point me to good links and possibly
books on all things hard drives including their physicall guts,

There isnt a lot except at the most general level.

tools to deal with them, ...?

The hard drive manufacturer normally has at least
a diagnostic and often a feature tool as well.

Something I notice is that some hard drives are placed
vertically in some computers and horizontally in some others,
but I think (actually it could be even proved) drives (their
mechanical parts) are a lot less taxed if they spin vertically,

Not necessarily, most obviously with modern fluid bearings.

but I don't hear of anyone talking about these kinds of things ...

The question of how drives can be mounted is a FAQ.

The short story with modern drives is that the manufacturers
say anything is fine, tho a few do say that any of the 90 degree
angles are fine with some of the older technology drives.

Laptop drive clearly couldnt care less.

 

[lbrtchx]

... not all ...
: Could you let me/us know which ones do? I promise I won't tell
anyone else ;-)
..

... smartctl doesnt work exclusively at the hardware level. It still gets access via the drivers.

: I see. That makes things clear. It is not so clearly stated in their
documents
..

Not necessarily, most obviously with modern fluid bearings.

: I am talking about the torque needed to reach a rotational momentum
to actually rotate the drive.
..
http://en.wikipedia.org/wiki/Torque
..
I would even say that there is a linear relationship (depending on the
lever) between the torque needed to move a flat cylinder (a platter)
horizontally and to move it vertically. I am a freaking physicist, if
you couldn't tell ;-)
..
I wonder how is it manufacterers would say it does not matter. I mean
I would even consider earth magnetism to place the drives in certain
ways
..
thanks
lbrtchx

 

[Arno Wagner]

After reading smartmontool's FAQ and a number of other tutorials/info,
I still don't quite understand why is it that smartmontool is not or
can not be used in a -software- RAID conf. I also wonder why not so
many people do this
.
if you do a search on 'smartmontools "software raid"', you will see
many people reporting "weird beaviors" and all kinds of other
unwanted/unexpected etceteras.

Huh? I have tested individual drives in software RAIDs with
smartmontools for several years and in > 20 computers wihout
any problems.

There is a question in smartmontool's FAQ, "Can I monitor disks behind
RAID controllers?", that address -RAID controllers-. However, since
smartmontool works on a hardware level and -software- RAID works on an
OS level basically, I don't see why smartmontool is not used in
-software- RAID confs?

It can be. Or would you be talking about Windows software-RAID
here? Then the answer would be that MS just did something
stupid to cause all these issues. On Linux it works perfectly
fine.

Also, could you point me to good links and possibly books on all
things hard drives including their physicall guts, tools to deal with
them, ...?

Something I notice is that some hard drives are placed vertically in
some computers and horizontally in some others, but I think (actually
it could be even proved) drives (their mechanical parts) are a lot less
taxed if they spin vertically, but I don't hear of anyone talking about
these kinds of things ...

Best dread a HDD manual. Maxtor has theirs online, as has Seagate
(I think). This would be 50-200 page documents telling you
most things you want to know.

Arno

 

[Rod Speed]

You've butchered the quoting back too far. That
phrase occurs in more than one of my comments.

Could you let me/us know which ones do?

Not possible to know which bit it came from.

I promise I won't tell anyone else ;-)

You promise on the life of your first born ?

I see. That makes things clear. It is not so clearly stated in their documents

Yeah, presumably they assumed the reader would realise that.

I am talking about the torque needed to reach a
rotational momentum to actually rotate the drive.

http://en.wikipedia.org/wiki/Torque

Doesnt say anything about any different torque
required with the platters vertical or horizontal.

And clearly when the hard drive manufacturers say that both vertical
and horizontal mounting is fine, they have decided that it doesnt matter.

I would even say that there is a linear relationship (depending on the
lever) between the torque needed to move a flat cylinder (a platter)

It isnt a flat cylinder, its a disk.

horizontally and to move it vertically.

That is just plain wrong.

I am a freaking physicist, if you couldn't tell ;-)

As seen in India with their BSc(failed) qualifications presumably.

I wonder how is it manufacterers would say it does not matter.

They've presumably calculated the forces involved in both configs
and have decided that their design handles them both fine.

I mean I would even consider earth magnetism
to place the drives in certain ways

Its a microscopic effect compared with the other torque effects.

 

[lbrtchx]

// __ Rod Speed

You've butchered the quoting back too far. That phrase occurs in more than one of my comments.

: Sorry! I meant your "Basically because not all software raid configs
allow that." Could you tell us which ones do?
..

As seen in India with their BSc(failed) qualifications presumably.

: Well, not exactly, I am not even Indian (nor do I have anything at
all against these people), but let's not get off-topic.
..
// __ Arno Wagner

Huh? I have tested individual drives in software RAIDs with

smartmontools for several years and in > 20 computers wihout
any problems.

It can be. Or would you be talking about Windows software-RAID

here? Then the answer would be that MS just did something
stupid to cause all these issues. On Linux it works perfectly
fine.
: Arno, I primarily work with Linux, FreeBSD. Software RAID using
smartmontool is something I would like to study/learn well. People
learn differently and I am teh type, that likes to learn stuff well and
back my tinkering actions by a mental map. I just can't afford doing
things in anyother way.
..
Concretely I live in NYC, keep my 9-2-5 commute a good 2.30 hours a
day ..., so I prefer to read/study in the train (mass transit) and go
home with a clear idea of what to try/do.
..
Are there any documents|scripts|links| ... you would be willing to
share?
..
thanks
lbrtchx

 

[Michael Heiming]

In comp.os.linux.hardware (e-mail address removed):

After reading smartmontool's FAQ and a number of other tutorials/info,
I still don't quite understand why is it that smartmontool is not or
can not be used in a -software- RAID conf. I also wonder why not so
many people do this
.
if you do a search on 'smartmontools "software raid"', you will see
many people reporting "weird beaviors" and all kinds of other
unwanted/unexpected etceteras.
.
There is a question in smartmontool's FAQ, "Can I monitor disks behind
RAID controllers?", that address -RAID controllers-. However, since
smartmontool works on a hardware level and -software- RAID works on an
OS level basically, I don't see why smartmontool is not used in
-software- RAID confs?

[..]

Dunno where you found this information but this is completely
wrong. 'smartctl' works just fine with softraid setups, as it
just looks on the physical hdd. Of course you have to tell it
which physical device to use, *not* the md device. '/proc/mdstat'
or/and whatever raidtools you are using should tell you which
physical devices build the array you need to query with
'smartctl'.

It doesn't work with hardware raid controller as the OS can't see
a real physical disk but just the device the hardware raid
controller presents as device. Which is already the raid array.

Dunno about fakeraid controller, I have never used such a crap.

Though I have mentioned from time to time there is a bunch of
completely wrong information out there if you search for
something. It can difficult for someone missing the experience to
see which information can be trusted and what is complete BS...

Good luck

 

[lbrtchx]

It can difficult for someone missing the experience to see which information can be trusted and what is complete BS...

: Well, yeah! This is obviously why I come here for help. It is not
laziness
..

Good luck

: Luck, you say? ;-)
..
lbrtchx

 

[Rod Speed]

Shit your quoting is an utterly obscene mess...

(e-mail address removed) wrote

Rod Speed wrote

Havent bothered to keep track of which ones do and which dont.

Well, not exactly, I am not even Indian (nor do I have anything
at all against these people), but let's not get off-topic.

Nothing off topic about it.

 

[John-Paul Stewart]

Michael Heiming wrote:
[snip discussion of smartctl and software RAID]

It doesn't work with hardware raid controller as the OS can't see
a real physical disk but just the device the hardware raid
controller presents as device. Which is already the raid array.

Have you tried the -d/--device option for smartctl? Apparently the
3ware driver and the cciss driver (for certain Compaq/HP SmartArray
controllers) can pass the SMART commands through to the drives (on
Linux, anwyway). I don't have a suitable controller to try, so I don't
know how well it actually works.

 

[Michael Heiming]

Michael Heiming wrote:
[snip discussion of smartctl and software RAID]

It doesn't work with hardware raid controller as the OS can't see
a real physical disk but just the device the hardware raid
controller presents as device. Which is already the raid array.

Have you tried the -d/--device option for smartctl? Apparently the
3ware driver and the cciss driver (for certain Compaq/HP SmartArray
controllers) can pass the SMART commands through to the drives (on

If you install the HP psp package you get all info and anything
you never wanted to know about those controllers. In addition it
can mail you any problem about all hardware and even order the
needed spare parts and some technician to replace them
automatically, if you like?

Linux, anwyway). I don't have a suitable controller to try, so I don't
know how well it actually works.

I have tried that and others, any try to access my 3ware
controller using smartctl ends up with a solid hard lockup.;(

But why bother, there is a cron job running hourly, checking the
output of:

tw_cli info c0 drivestatus

It will send me a mail if there should be a problem. 'tw_cli'
comes from 3ware to cli configure/etc your controller, works like
a charm. Once it stopped working with the latest kernel, went to
the 3ware Hp and in the beta section there was already an updated
version that worked again. ;-)